Heating control



April 27, 1937.- v LUM 2,078,802

- HEATING CONTROL v Filed Ju ly 14, 1934 Inventor:

Walter O. Lum,

. y l i zttorney' Patented Apr. 27, 1937 UNITED STATES HEATING CONTROL 7 Walter 0..Lum, Schenectady, N. Y., assignor to General Electric Company, a. corporation of New York Application .luly 14, 1934, Serial No. 735,128

. '7 Claims. (01. 237--9) The invention relates to heating control and provides improvements particularly advantageous in the control of a combined vacuum vapor room heating and domestic hotwater heating system and in other similar service.

The principal object is to insure that there is no vacuum in the room heating system whenever the heater is operated for heating the domestic hot water under automatic thermostatic control.

In the ordinary vacuum vapor room heating system, the vacuum insures a continued supply of heating vapor from the boiler to the room heating radiators even though the temperature of the water in the boiler drops considerably below the normal boiling point of Water. However, where the supply of domestic hot water is heated by means of a heat exchanger connected to the same heating boiler used in the vacuum vapor room heating system, the boiler water temperature ordinarily must be maintained at a value fairly close to the normal boiling point of water in order to providean adequate supply of domestic hot water at a sufficiently high temperature to be suitable for hot baths, washing dishes and the like. Consequently, when the ordinary vacuum vapor room heating system is provided with a heat exchanger for. heating the domestic hot water Supply heating vapor will be released from the boiler into the room heating radiators whenever the boiler water is maintained near the temperature required for satisfactorily heating the domestic water. This is very undesirable, particularly where it is desired to operate the heating boiler with an automatic fuel burner to supply the domestic hot water during. both summer and winter under the control of an automatic domestic water temperature control thermostat and also to operate the heating boiler under automatic room thermostat control.

In accordance with the present invention the difiiculty outlined above is efiectively overcome by means o'fan improved control which automatically releases the vacuum in the room heating system whenever the heating boiler is operated under the control of the automatic domestic water temperature control thermostat and permits the vacuum.

, the water in the domestic hot water supply tank l3. While the heat exchanger coil I2 is shown immersed in the water in boiler Ill, it will be understood that the ordinary externally connected supply hot water for domestic services such as The heat exj baths, washing dishes and the like. changer coil I2 is connected between the top and bottom of tank It! and serves by thermosyphon circulation to transfer heat from the water in boiler ID to the Water in the domestic water supply tank l3. I

A suitable form of automatic electric motor operated fuel burner 20, such as an oil burner, coal burner or the like is provided for heating the water in the boiler Ill. Steam and vapor is conducted from the space 2| in boiler Ill above the water level through the house heating supply pipe 22 to the room heating radiator H. The condensed steam and vapor is returned to the boiler through the return pipe line 23'. Radiator II is provided with the usual manual cutoff valve 24 and an automatic air vent valve 25 which may be of any well known form.

The operation of the automatic electric motor driven fuel burner 20 is started and stopped by means of a suitable electrically operated means indicated diagrammatically at 30 which is energized from supply lines Ll, L2 and may be of any well known type, which energizes the driving motor 20 to start the burner. in operation when the circuit is closed between terminals R and W and 35 deenergizes motor 20 to stop the burner operation when the circuit is closed between terminals S and W. Y

The room thermostat BI and the water thermostat 32 both effect operation of the control 30 to start and stop .burner 20. Room thermostat 3| is shown of the two-position type having both a run contact R and a stop contact S, with the movable thermostatic blade operable therebetween. The water thermostat 32 is shown as of the expansible bellows type having the bulb 33 immersed in the water in boiler l0 so as to be responsive to the temperature thereof. When the water temperature rises above a predetermined value, the bellows expands and opens con- 3' present invention, the electromagnetically operated vacuum relief valve 40 is connected to the vacuum vapor heating system, preferablybeing connected to the vapor supply pipe line 22 as indicated in the drawing. The vacuum relief valve 40 is normally biased to the closed position by a spring or other suitable means. The valve is opened when the winding of the operating electromagnet 42 is energized, thus permitting air from the atmosphere to flow directly into the vapor heating pipe line 22 and relieve any vacuum existing therein. However, as long as valve 40 is closed the Vacuum system remains sealed from atmosphere.

As shown the vacuum relief valve 4|] is provided with a circuit controlling contact 43 which engages with the cooperating pair of contacts 44 when the valve is closed and with the upper pair of cooperating contacts 45 when the valve is open.

The operation of the heating control illustrated is as follows. As shown the room thermostat 3| is in the midposition between the running contact R and the stopping contact S, thus indicating that the room temperature is at the normal value'which the room thermostat is set to maintain. The contact 34 of the water thermostat 32 is in the open position thus indicating that the Water in boiler I0 is above the temperature which is necessary to provide adequate heating of the domestic hot water supply by means of the heat exchanger i2.

In case the room temperature drops, room thermostat 3| closes on the running contact R. This establishes a circuit which causes the electrical control 30 to operate to start the automatic fuel burner 20. Upon operation of burner 20 the temperature of the water in boiler I0 increases and steam and vapor is supplied from the boiler I I] to the room heating radiator II. If there is any air in the radiator the supply of steam and vapor drives the air therefrom through the automatic air vent valve 25. However, valve 25 automatically closes to prevent escape of steam and vapor after the air is vented. The continued heating action of radiator Ii causes room thermostat 3| to move into engagement with the stopping contact S. Upon engagement of room thermostat 3| with stop contact S, a circuit is established which causes the electrical control 30 to stop further operation of the automatic burner 20. However, heating vapor continues to be supplied from the boiler ID to the radiator H due to the fact that as the steam and vapor condenses a vacuum is created which lowers the boilingpoint of the water in the boiler ill below the normal value. As long as the vacuum relief valve 40 is closed, the vacuum is effectively maintained in the radiator piping system and the supply of heating vapor to the radiator II can continue until the temperature of the water in boiler l0 has fallen far below the normal boiling point.

Whenever the temperature of the water in boiler 10 falls below the predeterminedvalue at which the water thermostat 32 is set to operate contact 34 to the closed position, "an energizing circuit for the operating electromagnet 42 of the vacuum relief valve 40 is established. The resulting operation of valve 40 to the open position at once admits air into the radiator piping system to relieve the vacuum therein and prevent further release of heating vapor from the water in boiler III to the radiators.

At the same time the contact 43 engages the upper pair of contacts 45, thus shunting the running contact R of the room thermostat 3| to cause the electrical control 30 to start operation of the automatic burner 20. This operation of the automatic fuel burner 20 heats the water in boiler I0 until the predetermined temperature is reached at which the water thermostat 32 opens contact 34. 'I'hereupon the energizing circuit of the vacuum relief valve 40 is opened and the valve closes in accordance with its bias. At the same time the contact 43 returns into engagement with the lower pair of cooperating contacts 44. This shunts the stopping contact S of the room thermostat 3| and serves to effect operation of electrical control 30 to stop the burner 20.

Thus whenever the burner 20 is operated under the control of the water thermostat 32, the vacuum relief valve 40 is always open. At the same time due to the fact that contact 43 disengages the pair of contacts 44, the room thermostat 3| is rendered inoperative while the burner 20 is being operated under the control of the water thermostat 32.

It will be evident that .the temperature of the domestic hot water in the tank I3 varies with the temperature of the water in the boiler l0 as well as with the various conditions of use of the domestic hot water. Consequently, when it is desired to increase the temperature of the water in the domestic water supply tank I3 it is only necessary to adjust the setting of the water thermostat 32. so as to maintain the temperature of the water in boiler [0 at a higher value. Thus in effect the thermostat 32 operates the burner 20 to'control the temperature of water in the domestic water supply tank i3.

While I have illustrated and described one form of control system embodying the improvements of my present invention, it will be understood that the invention is not limited thereto and can be carried out with considerable modi fication of the specific apparatus illustrated and described. If desired, the water thermostat 32 may be made directly responsive to the temperature of the water in the domestic hot water tank l3 instead of the temperature of the water in boiler Ill. Likewise the contact mechanism associated with the vacuum relief valve 40 may be controlled directly by the water temperature thermostat 32, if desired, as substantially the same results will be obtained. Likewise the vacuum relief valve 40 may be biased to the open position and operated electromagnetically to the closed position and various other changes may be made which will be obvious to those skilled in the art without departing from the principle of the present invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, a vacuum vapor room heating system having a boiler provided with an automatic fuel burner for heating the water therein, domestic water heating means connected with the boiler, a room thermostatand a water temperature control thermostat for separately controlling the operation of said burner, and a vacuum relief valve connected to be operated under the. control of said water temperature control thermostat to relieve the vacuum in the system upon operation of the burner under the control of said water temperature control thermostat.

2. The combination of a vacuum vapor room heating boiler, an automatically operable fuel burner for heating the water in the boiler, domes thermostats for effecting operation of said burns er to heat the boiler water to a temperature providing vapor under vacuum in the boiler,'a

vacuum relief valve connected with said boiler, and means simultaneously operable under the,

control of said water temperature control thermostat foroperating said valve to relieve the vacuum in said boiler upon operation of said burner under the control of said water temperature control thermostat.

The combination of a vacuum vapor room heating boiler having domestic water heating means connected to be heated from the water in the boiler, an automatically operable fuelburner for heating the water in the boiler, control means for starting and stopping operation" of said burner, a room thermostat for controlling operation of said,control means to heat the i boiler water to'a temperature providing vapor eration of saidcontrol means to heat the boiler under vacuum in the boiler, a water temperature control thermostat for separately controllingopwater to a temperature providing vapor under vacuum in the boiler, means operable under the control of, said water thermostat for rendering said burner control means unresponsive to the control of said room thermostat and a vacuum relief valve connected to relieve the vacuum in said boiler upon operation of said burner under t e control of said water temperature control liquid for operating said heating means when.

said temperature falls below a predetermined value under the normal boiling temperature of the, boiler liquid at atmospheric pressure, and valve means opened by said temperature responsive means when the temperature of the boiler liquid falls below said value for venting the boiler to atmosphere to prevent vaporizing the boiler liquid at temperatures below said predetermined value.

6. In combination, a boiler having heating means operable for vaporizing liquid therein under vacuum at temperatures under the normal boiling temperature at atmospheric pressure, means responsive to the heat transfer action of the vaporized liquid for controlling operation of said heating means, means responsive to the temperature of the boiler liquid for operating said heating means when the boiler liquid temperature falls below a predetermined value under the normal boiling temperature of the boiler liquid at atmospheric pressure, and valve means opened by said temperature responsive means when the temperature of the boiler liquid falls below said value for venting the boiler to atmosphere to prevent vaporizingthe boiler liquid at temperatures below said predetermined value.

7. In combination, a boiler for vaporizing liquid under vacuum, means operable for heating the liquid in said boiler, means in heat transfer relation with the vapor in said boiler, separate means in heat transfer relation with the liquid in said boiler, temperature responsive means associated with said vapor .heat transfer means for controlling operation of said heating means to regulate a predetermined temperature condition, means responsive to the temperature of the boiler liquid for controlling operation of said heating means when the boiler liquid temperature falls below a predetermined value under the normal boiling temperature of the boiler liquid at atmospheric pressure, and valve means opened by said boiler liquid temperature responsive means when the temperature of the boiler liquid falls below said value for venting the boiler to atmosphere to prevent vaporizing the boiler liquid at temperatures below said predetermined value. WALTER O. LUM. 

